The manufacturers of magnetic hard-disk drives (HDDs) are constantly under pressure to increase both performance and data storage density. Unfortunately, HDDs having high linear recording densities tend to suffer from nonlinear and linear distortions in their read/write channels, which may lead to significant performance degradation.
An approach used to identify such nonlinear distortion in HDDs is referred to as “dibit pulse extraction.” As dibit pulse extraction may be used to identify nonlinear and linear distortions, it may therefore be used to minimize their effects. For example, dibit pulse extraction may be used to determine the write precompensation and channel equalization that may optimize the bit-error-rate (BER) performance of an HDD.
Current dibit pulse extraction techniques can require a sampling clock significantly higher than an HDD's read/write channel clock. Given that HDDs may have channel clocks running at data rates of 2 Gbps or higher, it may not be practical to integrate the current dibit pulse extraction techniques into an HDD's read channel. Generally, a separate analyzer with a very high sampling clock is used to measure an HDD's distortions, which may be both expensive and difficult to implement via monolithic or hybrid integration.